For some time now, due to the rapid advances being made in the state of the art of the projection or lithographic printing field, it has become very desirable to be able to provide image geometries of less than about 1 micron and with very high device packing densities. In order to most advantageously obtain the same it has become desirable to employ projection imaging wavelengths in the deep ultra-violet (UV) region of below about 300 nm. Therefore, it has become necessary to provide solubility modification agents suitable for use with imaging wavelengths in the deep UV region.
The naphthodiazoquinones commonly used in non-deep UV resist compositions are of very limited usefulness in deep UV photoresists because of their excessive and non-bleachable deep UV absorbance. In U.S. Pat. No. 4,339,522 of R. Balamson et al., issued July 13, 1982 and assigned to International Business Machines Corporation, there is disclosed a deep UV resist composition which comprises phenolic-aldehyde resin sensitized with Meldrum's acid diazo or a homologue thereof. However, the image resolution characteristic of such a composition leaves much to be desired. More recently, in U.S. Pat. No. 4,624,908 of George Schwartzkopf, issued Nov. 25, 1986 and assigned to J. T. Baker Inc., there is disclosed deep UV positive photoresist compositions of improved image resolution characteristics providing good resolution of 0.75 micron lines or smaller. The novel solubility modification agents disclosed in said patent are certain 2-diazo-1,3-dione compounds.
However, it is desirable that deep UV solubility modification agents be available which possess greater photosensitivity than said 2-diazo-1,3-dione compounds, i.e. which exhibit a more rapid response to deep UV light thereby allowing shorter exposure times to achieve the same extent of photoreaction. Additionally, it is highly desirable that photoresist solubility modification agents be available which allow for image reversal (from positive to negative) to be achieved with these agents simply by changing developer type from metal ion containing to metal ion free developer. It is further desirable that deep UV photoresist solubility modification agents be available with the above-stated advantages and which also provide for the good image resolution of 0.75 micron lines or smaller.